A modulator fundamental part of Mach Zhender interferometer is studied. This interferometer has applications such as a sensor or spectral analyzer. The modulator was designed on a SOI substrate comprising a dual capacitor structure that allows the electro optical modulation through the overlap of the plasma dispersion effect (variations of the free carriers density due to electric field induced carrier depletion) with the guidewave mode that induce the change of the effective refractive index. The modulator is excited by a tension ramp between 0 and 2V yielding performance exceeding 7 GHz.
In this work, it is study thermoluminescent phenomena (TL) optically stimulated with UV radiation in Silicon Rich Oxide (SRO) nanostructured thin films. The experimental samples used were thin films of this composite deposited by Low Pressure Chemical Vapor Deposition (LPCVD) over a n-type silicon substrate, this samples were fabricated using different flow ratios of precursory gases silane and nitrous oxide R0=SiH4/N2O during the deposition and were given posterior thermal treatment which gave place to the formation of different sized nanoparticles, that are attributed to the luminescent activation mechanism in this material. The silicon excess was controlled by the ratio of the gases used in the deposition process and in this way SRO films with 12, 8 and 6% silicon excess were obtained. The glow-curves experimentally obtained were submitted to analysis using different models in order to obtain important thermoluminescent parameters. The luminescence spectra of SRO show two wavelength regions of emission; one in the blue part and one in the red part of the emission spectrum. The emission in the blue part is related to defects in the SiO lattice. About the origin of the red luminescence there is still a controversy. One model assumes that the red luminescence stems from Si nano particles and another model assumes that defects at the interface of SiO bulk with the Si nano particle are responsible for the red luminescence. Finally is intended to provide favorable conditions for the development of a UV dosimeter with this material.
KEYWORDS: Cadmium sulfide, Thin films, Annealing, Solar cells, Transmittance, Thin film solar cells, Atomic force microscopy, Crystals, Cadmium, Electro optics
In this work we report the fabrication and electro-optical characterization of CdS thin films using glycine as complexing agent with ammonia and ammonia free buffer by the Chemical Bath Deposition (CBD) method. The CdS thin films were grown at different temperatures of 50, 60, 70 and 80 °C in a thermal water bath. The morphology of these films was determined using atomic force microscopy; the resultant films were homogeneous, well adhered to the substrate, and specularly reflecting with a varying color depending on the deposition temperature. Transmittance and reflectance measurements of thermally treated CdS films were carried to study the effect of the ammonia buffer on its optical properties and bandgap. The crystallinity of the CdS thin films was determined by means of X Ray diffraction measurements. Therefore, for this study, an ammonia-free complexing agent has been taken for the deposition of CdS. Among different methods, which are being used for the preparation of CdS films, Chemical Bath Deposition (CBD) is the most attractive due to its low cost, easy to handle and large possibilities regarding doping and deposition on various substrates. In particular it can be used to easily obtain field effect devices by depositing CdS thin films over a SiO2/Si substrate. Heterostructures with interesting physical properties can be imagined, realized and tested in this way.. Structures CdS/PbS also were realized and have shown good solar cell characteristics.
In this paper we describe an analog microwave photonic link system used to transmit simultaneously two TV signals.
The experimental setup is composed mainly by two distributed feedback (DFB) laser diodes emitting at 1500 nm. When
DFB lasers are operated in the low laser threshold current region, relaxation oscillation frequencies are obtained.
Relaxation oscillations in the laser intensity can be seen as sidebands on both sides of the main laser line. The optical
emissions generated in each laser are combined and amplified by using an Erbium-Doped Fiber Amplifier (EDFA).
Next, the amplified optical signal is detected by a fast photo-detector using direct detection method and as result of this
photo-detection microwave signals are generated. Microwave signals obtained by this technique are used as electrical
carriers to transmit analog TV signals over 30 km of standard optical fiber by using a Mach-Zehnder modulator (MZM).
At the end of the optical link the modulated light is photo-detected in order to recover efficiently and successfully the
analog TV signals.
Optical microspectrometers have huge potential for application in industry, science, medicine, agriculture and biology.
The actuallity is towards fully integrated optical microsystems. Complete silicon IC compatible MEMS-based optoelectrical
microsystems on a single chip. This systems however, impose limitations. The required process compatibility
and limited choice of acceptable materials does not necessarily give high optimal optical performance. This work study
the best characteristics of micromirrors fabricated with anisotropic etching and used in spectrophotometers and endedended
systems. The trends, the potential, the limitations and approaches to obtain a sufficient optical performance, in
terms of spectral resolution and throughput, for serving the majority of applications.
In this work, a photodiode for the visible spectral range, which will be integrated monolithically with CMOS circuits, is
presented. Such Optoelectronic Integrated Circuit (OEIC) with high sensitivity in the 400-900 nm spectral range is
utilized to realize electronic processing from the light beam position that hit a specific area of the photodetector. The
output signals with voltages of 0V and 3 V can be implemented with a controller circuit. By the Using of He-Ne Laser
at 633 nm as incident light, the responsivity of the Position Sense Photodetector (PSPD) was 0.35 A/W and the rise and
fall time of less than 30 ns were achieved. These parameters were necessaries to achieve the photodiode integration in an
industrial 0.5 μm CMOS process, only additional mask was needed in order to block out the threshold voltage
implantation in the photo-active region. Therefore both designs of photodiode and the electronic processing circuit
separately, are shown here, all design will be integrated monolithically in the same Silicon chip.
This work shows the design, fabrication, and optimization of a silicon sensor with an extended sensing range toward the UV region. The main characteristic of this detector is the enlargement of the common silicon detection range to the ultraviolet region (240 to 400 nm). The fabrication process of this detector is compatible with complementary metal oxide semiconductor (CMOS) silicon technology, which makes it cheaper than commercial UV detectors.
In this work a Silicon/Silicon Rich Oxide (SRO) Ultraviolet detector is designed, fabricated and characterized.
This device increases the silicon detection range to the ultraviolet region (200-300nm). Besides the fabrication
process of this detector is compatible with standard silicon technology that makes it cheaper than commercial UV
detectors.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.